1. Field of the Invention
The present invention relates to computer system memory, and more particularly to controlling a voltage supplied to computer system memory.
2. Background of the Related Art
Modern server systems are being configured with increasingly powerful memory systems. The increase in server memory capacity is being achieved, in part, by both advances in memory module technology and the ability of system boards to support a large number of memory modules. The system boards of a modern server may have connections to support many DIMMs (dual in-line memory modules), for up to several terabytes (TB) of DDR3 (double-data-rate three) memory. The power and performance capabilities of memory systems are continuously under development. As a result of these trends, the voltage at which DIMMs are operated more significantly affects the power consumption and performance of the entire server.
One advance in memory module technology is the development of DIMMs operable at a lower voltage. Another advance in memory module technology is the ability of a given set of DIMMs to be operable at multiple voltages. For example, DDR3 SDRAM (double-data-rate three synchronous dynamic random access memory), which originally operated at 1.5V, now includes a DDR3L variant capable of operating at either 1.35V or 1.5V. In operating a computer system with a memory system having multiple voltage settings, a user is conventionally prompted to select a desired voltage when the computer is starting up. The user must reboot the system in order to select a different voltage.